Method of producing nitrogen-hydrogen mixture for the synthetic production of ammonia



Dec. 7 1926. 1,610,076

l F. W. DE JAHN METHOD OF PRODUOINO NITROGEN HYDROOEN MIXTURT FOR THE SYNTHETIC PRODUCTION OF AMMONIA y Filed sept. 21, 1923 GHS HOLDER MN.-

TTOHNEYS UNITED STATES 1,610,076 PATENT OFFICE. f

-FRRDRIR w. ne .AHN/oFNEW YORK, N. Y., AssIeNoR 'ro ATMOSPHERE NITROGEN l CORPORATION,A or soLvAY, NEW YORK, A CORPORATION or NEW YORK.

METHOD F PRODUCING NITROGEN-HYDROGEN MIXTURE FOR THE Sf '1\l'TIIE'2lIGl PRODUCTION AMMONIA.

Application tiled September 2l., 1923; Serial No. 663,961.

The invention relates to the process of pro-y ducing a gas mixture sultable for use, when i compressed and purified vunder said pressure,

as catalysis gas for making NH3.

5 In my application,.Serial No. 200,047 filed November 3,1917, I have described a method of producing such gas vwhich conslsts in adoptin a suitable system of regulation vat the gas ouse to produce a gas mixture containing for each volume of nitrogen; approximately three volumes of h drogen and carbon monoxidetaken together and then by catalysis in the presence of steam causing the CO to'be oxidized to CO2 withthe production of an equal volume of hydrogen. Inasmuch, hoivever, as the process described in said specification called for the use of a heat-- ing flame IWhen the temperature in the vicinity of CO catalyst tended `to become too low and said flame introduced into the-gases, just prior to the. catalysis of CO and steam, an additional quantity of nitrogen, the gas house regulation necessarily required at such times a corresponding' deviation such as to cauie the production of a gas in which there was intentionally a deficiency of nitrogen corresponding to theI additional nitrogen so introduced.' vIn thisway the desired 3:,1 gas mixture was continuously obtainedl even during those periods when the auxiliary burner Was -being operated.'

Although the fundamental .principle of this part of my former invention remains the same, i. e. catalyzed should contain for each volume of nitrogen approximately three vlumesof hydrogen and carbon monoxide taken together nevertheless, Irha've'subsequently found that it is by far the better practice not to use 'the auxiliary burner intermittently and las the means of temperature regulation but to use it continuouslyfor the purpose of fine and final adjustment of the nitrogen ratio in accordance with which it is operated`practical ly continuously and at the same time, the gas house operation is so conducted that generally speaking the composition of the gas mixture always approaches that of'a 3 1 mixture but is continuously, uniformly and 5 `intentionally maintained alittle low in nitrogen. v p

While it ma be possible toso regulate the operation of t e gas produ'cer as to produce directly and continuously a gas of the rethat the gas 'mixture to be quired 1:3 ratio, this is'in practice a ditii- 65- cult Operation. Operating conditions vSuch as variations in the depth and temperature ofthe fuel bed in the gas producer and the quality of the fuel-,Which conditions of necessity vary in operation-atect the ratio in the resultant gas even when the air-#steam ratio is maintained* constant. The gas comosition also varies during the period of each lndividual run. It might seem that while. su/ch variations do exist they could be treated as incidental and that the average composition for a reasonable period of time would be substantially constant. It is found,'how ever, that the fresh gas entering the gas holder from the as producer does not so mix with the gas in' the holder that the gas passing out of the holder to the CO converter v'system will be a gas xof the average composition 'but on the contrary the gas at times tends to stratify in the gas holder the composition of each stratum corresponding to the lgas entering the holder and therefore y produced during any given period. The fluc- `tuations in the composition of the as from the producer, some of which as a ove are unavoidab e, -are consequently in part 'and under cert in, circumstances transmitted directly to the CO system and thereby in turn Ito the synthesis system.

For 'these reasons it is preferred not to re a5 ly 'upon the gashouse to ratio in the as. It isusua to maintain a reservetgas supply (gas holder)4 between the gas house and the C() oxidation system so that a constant and regulatable flow of'rgas can be supplied to the latter independent of the existing flow from the gas house andthe variations in that flow including those times when the gas' produce a perfect house is not operating. Even assuming then 9 tha-tit was possible to obtain a gas of the desired composition directly from the Agas house such means of regulation is not available when the gas house is not operating, and even when available, because ofthe intervening storafe vessel, the effect thereof is not immediately and' directly transmitted to the ammonia synthesis system. y

By my new process these difficulties of the old process are overcome, Any deticiencyfin nitrogen of the crude gas entering the CO oxidation system is easil and accurately compensated by vthe intro uction of products of Iloof .combustion of regulated volumes of air and of a combustiblel gas and this means o-regulation is alwa s and immediately available; and the socal ed auxilia burner heretofore referred to may be used Itbr this combustion.

The invention is illustrated in the accompanying drawin J In that drawing it will be assumed that a nitrogen-hydrogen-carbon monoxid gas is made at the gas house byptreating incandescent coke with a regulatedl mixture of air and steam. This air and steam is preferably so regulated that while thelnitrogencarbon monoxid plus ihydrogen ratio aproaches 1:3, it does not reach this value ut is consistently and intentionally maintained below. This crude gas after suitable cooling and purification is storedjn a gas holder. The gas from the gas holder enters the carbon monoxid oxidation system throu h the line 1, whence the blowers2 prope it through the line 48 into one end of a preheating system 47, 49, 5,1, 47249, 471 and through 52 into the converters 39 (which are illustrated as operating in parallel). lThe converted gasr leaves the converters 39 at43 and passes back through the v heat interchanger system 47", 44, 47", 45, 47,

inally leaving said system through pipe 46. The pipe 46 conveys the gases to condensers 4 and thence through 5 to the gas holder 'and ultimately to the large compressor of the purification and ammonia synthesis system. l

The re uired Steam for the catalytic reaction (C +H2O=CO2+H2) may all of it be introduced directly as low pressure steam through pipe 48, entering the incoming gas in 48a at A, the steam being metered at 11, orr the heat of the outgoing vconverted gas may b e used in part to produce 1n situ a certain amount of the required steam content of the reaction gas mixture; This may be accomplished Vby operating the first interchanger 47 in the, manner invented by -lWalter H. Kniskern, and described inhis application, Serial No. 663,956 of September 21, 1923, i. e.,'as a so-called wetted tube interchanger in'which water is continuouslyl circulated byl pumpB and pipe C into the top of the interchanger 47'f`and dis' tributed so that it trickles down over the inside surface of the interchanger tubes and in intimate contact with he from 48. The result is that the w er becomes heated i by heat interchange' with the hotconverted gas rom`45 and Water vapor (steam) is evaporated -into the raw gasfrom the circulated water atthis temperature. The excess water is reciroulated, the volume @foir-v culated water being lmaintained lconstant by v -terchanger 47 is Aaddition of fresh water. When the first inthus used.. as a wetted tube interchanger no steam is added at A but the balance of the required steam is added troduced.

ed at the auxiliary burner. 8. To this end 'a n ieasuredquantity, of air l,supplied by blower 6 is introduced by the burner 8 through lines 7 and 7 and at the -fsame time a. measured quantity of the gas entering the system through'48a is withdrawnat 9 and introduced into the burner. The quantity of the gas so introduced is at least equal-to 'i and `preferably somewhat in excess of `that required for complete combustion of the air v introduced. vThe as and a'ir can be .conveniently measur by meters y10 and 17 )situated in the i gas and air lines.` In prae-V tice the crude gas (the gas in 48) and also the gasv after compression and puriiication and the gas circulating inthe ammonia synthesis vsystem propery areconstantly analyzed at short intervals. The7 air supplied at 8 is then regulated accordingly, the air, fof course, bein a measure o the mtrogen inliviously, anyl combustible gas could be used in the burner 8 which would burn with the oxygen of the introducedair -and which would not introduce any objectionable impurities into the'g'as system. Inasmuch, however, as the crude gas (in 48") IDH is produced as part of the process and is,

`dicated ,in the drawings, immediately in adlVance of the catalyst, so that it may also serve as a source of heat for the catalytic reaction. Although this is the referred point in the system for applying t e. nitrogen' regulation, it is manifestly possible to effect 'the nitrogen regulation ati other parts of the gas circulating system illustrated in the drawings, as for example in the gases on theirway to catalysis or after catalysis.

The less of the gas from 48* burned at 8 i thev better and more economical will be the operation of thesystemv as awhole andl this in turn means that the gas housev practice,

should, in the preferred method of operating, according to my. process, continuously strive fora ratio of 3 :(1-X), vin which Xis 'less than one and the smaller X is. the better. In, other words, the preferred process is not to strive for a perfect ratio 3:1 at the gas -house but for an. approximate ratio. .at thegas/x-house, say 3:2/3 with intentional sonably accurate nitrogen injecting 'control vadjustment of the nitrogen-hydrogen ratio.

4. Economical. It has been proposed to add4 all or practically all the nitrogen as air at'the auxiliary burner. This involves a large loss of hydrogeir-either as hydrogen or carbon monoxide-in the combustion of this air in the auxiliary burner.

5. Source of reserve heat.

The burner will sup ly a certain amount of heat to the system Wliicli, although it may not be essential to successful o eration, is available if needed. Further, if igor any reason the reaction temperature in the coiiverter should .become abnormally low andv cannot readilybe adjusted in any usualuinanner, the required heat can at once be supplied by temporarily increasing thesupply of air to the burner. v

6. The practical result is that two inde'- peiident means of nitrogen. control or adjustment are available; y

(a) The gas house operation is available for correction of relatively great deviations4 from the'desii'ed ratio, for preliminary and rela-tively vcoarse adjustment and for Cases where the adjustment may be made gradm' ally or is not desired immediately.

(7)) The auxiliary burner is available for fine, final and immediate adjustment ofthe ratio. l i

In practicing the invention of this application it is to be understood that the crude nitrogenhydrogen-carbon monoxide' gas may be produced by any desired method. Such a gas would result, forexample, by mixing gas trom` two producers, one oper` ated to produce lwater gas (mainly CO roduce and H) andthe other'operatedto N) .or

producer gasf (mainly/@0, H an .,.by adding to water gas some of the gas vpeproducedvduring the blast or heating N) riod-blast gas (mainly CO2 CO an etc. In thecase of such a gas made byy mixing two Separate and different gases the addition ot the.oiie to the other can be so regulated as to give the approximate'desired ratio. the final ratio regulation being per-- formed by the auxiliary burner or itsequivalent;

Numerous modifications may obviously be e required nigas the nitrogen required made lwithout departing from the scope of "this invention.

I claim: l A l. Ihe -processcof producing a gas mixture containing nitrogen and hydrogen in a predetermined ratio `which consists in preparing a gas mixture of nitro en, hydrogen and carbon monoxide inl whici `the ratio of nitrogen to hydrogen plus carbon monoxide is less than the desired predetermined ratio of nitrogen ,to h .drogen treating this gas with steam in te presence of, a catalyst whereby CO is oxidized to C02 with the production of an equal volume of hydrogen and prior to the completion of the catalytic reaction supplying to the gas the deficiency in nitroge by burning regulated quantities of air in he gaseous system.

l 2. In the process of producing a nitrogenhydrogen gas mixture. in a predetermined ratio suitab e for ammonia' synthesis by treating a nitrogen-hydrogen-carbon monoxide gas mixture with steam in the presence of a catalyst adapted to the oxidation of CO to C()2 and-the production of an equal volume of hydrogen, that improvement which consists in preparing 7a crude gas mixture' iii which the ratio of nitrogen to hydrogen y plus carbon ,monoxide is less than the desired predetermined ratio of nitrogen to hydrogen and subsequently, during the treatment of the gases prior vto\ammonia` syn-y thesis supplying the deiciency'in `nitrogenI 'by the addition 'to.the gas mixture of the gaseous result from the combustion of air with a portion of the gas in quantities reg` ulated with reference tovsaid deficiency.

:3., In the process of producing a nitrogen-k hydrogen gas mixture suitable for ammonia synthesis by treating a nitrogen-hydrogen` carbon .monoxide gas mixture with steam in the 'presence of a catalyst that im roveinent which comprises sup lying to t e gas' any deficiency in nitrogen adding to .said gas prior'to the completion of the catalytic reaction the gaseous'result from the combustion of air with a combustible gas in. uantil ties regulated with reference to sait deicie'ricy.

' 4. The process of producing a gas mixture intended for ultimate use. as catalysis gas for makino' ammonia, which consists in treating incandescent carbonaceous material with controlled amounts of air and steam to produce a crude mixture in which the hydrogen plus. carbon-monoxid content by. volume is more than threetimes the nitrogen content by volume and then suppltying to the crude or a' gas mixture', after COl conversion, 'containing hydrogen and nitrogen in the proportion of 1:3 by volume by introducing regulated amounts oi?I air at an auxiliar burner opening into the gas priorto ther O conversion, consuming oxygen oi thesaid air, and treating the gas mixiso " to aproduce a crude mixture in which the ture, as thus modified, for conversion of` its CO t0 C()2 with the production of corresponding voluines of hydrogen.

i 5. The process of producing a gas mix= ture intended for ultimate use as catalysis gas for making ammonia, which consists in treating incandescent carbonaceous mate@ rial With'controlled amounts of air and steam rogen plus cai'bon-inonoxid content by yolume is more vthan three times the nitrogen content by volume and then supplying mixture as thus modified for conversion of its -CO to CO2 with the production of corresponding volumes of hydrogen.

intended or ultimate use as catalysis gas for makingammonia, which consists in treating* incandescent carbonaceous material withv controlled amounts of air and steamto produce a crude mixture in which the hydrogen plus ,carbon-monoxid content by volume is more than three'times the nitrogen content by volumeA and then supplying tothe crude gas the nitrogen required for a gas mixture l after CO conversion, containing hydrogen and nitrogen'in thel proportion of 1 3 by voltime by introducin air at an auxiliar ygas prior Ato the regulated amounts of urner opening into the O conversion, consuming oxygen of the said air and also supplying'to said burner regulated amounts of s from the same sourceas the unconverte gas en`ln vtering the converter, treating the 'gasl mix? turelas thus modified for conversion of4 its CO to C()2 with theproduction ofcorre-A sponding volumes of hydrogen,- a'nd main-ff `In testimony whereof- I have hereunto set taining the heat require at the? converter by',

passing the converted gases intoheat exchange relation with the incoming uncon'- Y .verted ga's and in said heat exchange system correcting temperature deliciencies or excessesobserved in the converter.

7. The process of producing a gas mixture intendedfor ultimate use'as catalysis gas for making ammonia, which consists in treating incandescent carbonaceous material with controlled amounts of air and steam to produce a, crude mixture inwhich the hydrogen ,plus carbon-monoxid content by volume is more than three times the nitrogen content by volume, but in which the ratio of 3:1 is approximated, and then supplyintg to the crude gas Ythrough a regulatab e ame. the

balance of nitrogen content required for tlie o production of a gas mixture containing hydrogen and nitrogen in the proportion of 1:3 by 'introducino' regulated amounts of air at an auxiliaryrburner opening into the gas prior to the conversion and at the said burner consuming oxygen* of the said air and then treating the gas mixture as thus -inodiiied, for conversion of its CO to C()2 with the production of corresponding volumesof hydrogen. 6. TheJ rocess of vproducing a gas mixture 8. The process of producing a -gas'mixl ture intended for ultimate use as catalysis. y

gas for making ammonia, which consists in treating incandescent carbonaceous material with controlled amounts of air and steam to produce a crude mixture in which the hydrogen plus carbon-monoxid content by volume is more than three times the nitrogen content by volume but in whichv the ratio of 3:1 is approximated,\and then supplying to the crude gas through a regulatable flame the balance of nitrogen content required for thepprodiictionof a gas mixture containing hydrogen and nitrogen in the proportion of i 1:3 by i introducing regulated amounts of air at -aii auxiliary burner opening into the gas prior to the conversion and at'the said burnerjconsuming oxygen of the said air and also lsupplying to said burner regulated 4 amounts of gas from the same source as the unconverted gas-entering the converter.

'mi ,hand- FREDRIK W. DE JAHN. 

